PHILADELPHIA (AP) — A day before killing four people in a mass shooting in Philadelphia last week, authorities say the gunman went to his first victim’s door wearing a dark mask, shot through it and yelled that he was law enforcement before entering the home and continuing to shoot, police officials said at a news conference Monday.

The details were revealed a day after police announced that it was likely Joseph Wamah Jr., 31, had been killed in the early hours of July 2, as police had initially thought, and that a 911 call reporting the gunshots had been misrouted to the wrong neighborhood.

Officials said they have not found a connection between Wamah and the suspected shooter, Kimbrady Carriker. Authorities believe Carriker, 40, fatally shot Wamah in the early hours of July 2 and then, about 44 hours later, opened fire randomly with an AR-15-style rifle, killing four others and wounding four more in a southwest Philadelphia neighborhood.

Wamah was killed in a row house on South 56th Street, but Philadelphia Police Commissioner Danielle Outlaw said Monday that officers were dispatched several miles away to North 56th Street instead. Upon not finding any evidence of a shooting there, Outlaw said the officers asked dispatch to call back the 911 caller. She declined to discuss details of that follow-up call.

“I will abstain from providing the details of that interaction as they are currently under internal investigation," Outlaw said.

Outlaw said the call came in to dispatch about 2 a.m., nearly 90 minutes after the shooting was believed to have happened early July 2. When asked how she would respond to people in the neighborhood suggesting that if officers had gone to the correct address, it might have prevented the shooting Monday, Outlaw pushed back against the line of thinking.

“I caution individuals to go down that rabbit hole. We can coulda, shoulda, woulda all day ... That doesn’t make anyone feel better,” Outlaw said. “It’s tragic, it’s unfortunate. We don’t like the fact that we are adding to the atrocities that occurred,” she added.

Outlaw said because the injuries Wamah sustained were so extensive, she did not believe officers could have saved Wamah's life if they had been correctly routed.

Calls and emails to Wamah's family members seeking comment were not immediately returned Monday.

Meanwhile, while the dispatch response is being investigated, Outlaw said the department has instituted another failsafe to try to prevent calls from being wrongly marked as unfounded. She said a higher level of supervisor will have to review and OK it before a call is dismissed.

Deputy Commissioner Krista Dahl-Campbell said when 911 calls are received, the system identifies a location for the caller. Dispatchers have the option of automatically transferring that location to dispatchers, but in this case and in most cases, the operator inputs the location by hand.

“Oftentimes you are not calling about yourself ... so they end up inputting the reported information instead,” she said.

Outlaw and others said several times that the caller did not specify north or south during the report. Once officers checked the location they were routed to, asked for the callback, and checked again, the call was reported to be unfounded in the system.

Deputy Commissioner of Investigations Frank Vanore said police are still investigating a motive in both shootings. Carriker has been charged with five counts of murder, attempted murder, aggravated assault and weapons charges.

Vanore said it appeared the same weapon was used in the attacks. He had previously said both the AR-15-style weapon and a handgun found on Carriker after the shootings were self-manufactured weapons also known as ghost guns.

Vanore also said if he had not been familiar with Carriker since he was taken into custody, he would not have been able to identify him from the surveillance video gathered in Wamah's shooting because he was wearing dark clothing and a mask covering his face.

A representative of the Defender Association of Philadelphia, which is representing Carriker, said Monday they did not have a comment on the timeline changes or allegations from police.

Police called to the Kingsessing neighborhood on July 3 around 8:30 p.m. found gunshot victims and started to help them before hearing more shots. Some officers rushed victims to hospitals while others ran toward the gunfire.

Officers said witnesses and video of the attack indicated the suspect went to several locations while wearing a ski mask and body armor, carrying the AR-15-style rifle and shooting people and moving cars at random.

Cornered in an alley, Carriker surrendered and was found to have two guns, extra magazines, a police scanner and a bulletproof vest, police said.

Lashyd Merritt, 21; Dymire Stanton, 29; Ralph Moralis, 59; and DaJuan Brown, 15, were all killed in the July 3 attack. A 13-year-old and 2-year-old also suffered gunshot wounds and two others, including a 2-year-old, suffered wounds from shattered glass, police said.

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Associated Press reporter Mark Scolforo in Harrisburg, Pennsylvania, contributed to this report.

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